1. Field of the Invention
This invention related to improvement in a liquid ejecting apparatus, and in particular, to improvement in a liquid ejecting apparatus of an ink-on-demand type.
2. Description of the Prior Art
A liquid ejecting apparatus, particularly, that used for recording, has a recording head (a liquid ejecting head) provided with a fine ejecting conduit communicating with a fine liquid ejecting orifice. Therefore, when the apparatus is not operated, the liquid such as ink in the fine ejecting conduit often coagulates or is dried resulting in clogging the conduit. Or during transferring the apparatus, the vibration or impact often causes retreat of the meniscus formed at the tip of the ejecting conduit resulting in formation of the undesirable quality of images or inoperability of recording. During conducting the ink jet recording, fine fibers from the recording paper, dust in the ambient air, impurities in the ink and the like often cause clogging of the ejecting conduit resulting in inoperability of recording or poor quality of the recorded images. Therefore, a means for forming a negative pressure such as suction pumps, suction bombs and the like is, heretofore, attached to the tip of an ejecting conduit when necessary so as to suck the ink to clean the ejecting conduit, or an ink dissolving liquid is applied to the tip of the ejecting conduit to dissolve the solidified ink resulting in restoring the liquid droplet ejection. Though the conventional methods are effective when ink is present in the ink tank, when no ink is present in the ink tank, air is sucked into the liquid conduit in the recording head and this causes inoperability of recording or formation of poor quality of images.
In addition, according to conventional examples, such a state that no ink is present in a movable ink tank is caused by excess suction, inoperability of ink supply from a fixed ink tank due to clogging of the communicating path between the movable ink tank and the fixed ink tank, or vaporization of ink at the movable ink tank or the ink supplying path. In such a case, it is necessary to fill the movable ink tank with ink in advance as a pretreatment for sucking ink to restoring the ink jet recording. However, where the means for filling ink and the means for sucking ink for restoring the recording are independent from each other, upon occurrence of inoperability of recording or poor quality of images, it is not possible to determine wheather the ink filling means or the sucking means is the cause of the trouble. If the suction is conducted by mistake when no ink is present in the movable ink tank, it is not possible to restore the recording. In order to solve such problems, it has been proposed heretofore, for example, to detect the amount of ink remaining in a movable ink tank and that in a fixed ink tank, but the mechanism is complicated and the apparatus can not be simplified and minified.